ブラウザ実装状況

Gecko に関する注記

Starting in Gecko 9.0 (Firefox 9.0 / Thunderbird 9.0 / SeaMonkey 2.6), the ownerDocument of doctype nodes (that is, nodes for which Node.nodeType is Node.DOCUMENT_TYPE_NODE or 10) is no longer null. Instead, the ownerDocument is the document on which document.createDocumentType was called.